Gun sight training device



June 8, 1948. ALBLOOD EI'AL 2,442

GUN SIGHT TRAINING DEVICE V Filed Oct; 28, 1944 2' Sheets-Sheet l l-aser 51.

ATT N Y. v T

N INVENTORS 2 Sheets-Sheet GLEN/v INVENTORS ALB/512T BLOOD BY ART 2 A. BLOOD El AL GUN SIGHT TRAINING DEVICE June 8, 1948.-

Filed Oct. 28, 1944 -AT' ORNEY.

Patented June 8, 1948 PAreNr orrlca Philip Glenny, Hanworth, England, assiznors to Brentiord, EnI l The sp r -g f pe Company, ma,

Application October 28,1944. SerialNo.562,028 p 1 rncrmBr i n July 15,1943 l a i This invention relates to improvements Km. training devices for use with gun-sight apparatus r and has for its principal object the provision of improved means for enabling an instructor'to check the manner in which a gunner undergoing instructionis controlling such apparatus; In

aiming at his target (whichis generally a moving,

one) the gunner should keep a line of sight'de- Justment. When a gunner is undergoing training with such apparatus it is usual for an instructor to provide a moving dummy target, such as a model of an aircraft, oran'image'of atarget projected on a cinematograph screen. Hitherto there has been nousimple method by whlchgan instructor can check the accuracy of a gunners control of the direction of a; line of sight, or the adjustment of range setting apparatus during such training. The present invention provides a device that enables an instructor to carry out a such checks and, as a subsidiary feature, means to partake in the angular movement of the gun for which corrections are to be computed and in which a correction is automatically calculated by the computing mechanism on the basis of the angular rate of movement of the gun and is so applied as to displace theline of sight from the line of the gun through an angleequal to the cor-. rection angle to be imparted to the said gun.

Such sighting systemsare known as disturbedslght systems, and, in using them, had operation oi the controls may lead to considerable errors,

as a result of the reaction of the gun velocityon the line of sight, through the computing inech- 1, anism; it is therefore highly desirable to ensure; that an instructor shall be able to check the degree of accuracy of the control of the sight light projector is so associated with the sighting apparatus that a beam of light can be projected on to a dummy target, .or a projected image oi a target, towards which the line of sight is directed, the projector being coupled with the sighting apparatus in such a manner that the axis of the 9 Claims.

Furthermore, in a preferrediormroi theinvention, g

as applied to a sightin whichrangesls deter-w a mined by matching the apparent diameterrofuf. I r e 3 the target as seen by the gunner withan: adjust-. V able irameor system of spaced markings, which is adjusted by the gunnento have the *same ap-I parent; diameter asthe target, means arekpro -i vided to varyrthe diameter ofjthe projected beam y, and these; means. are connected, to the range-5 p setting adjustment oithe sightin such awayithat j the diameter oithe beam atagivendlstance from theproiector is made proportional to the ap-@ parent diameter of the adjustable frame. Seeing J r that the target employedlis not usually circular I (it might, for example, befa' moving model or a movingimage of an aeroplanelthe expression, "apparent diameterof the target? must be'under stoodto include the diameter of an imaginary circle framingthe whole or a partof thetarget i I '3 acrossairnown dimension thereof (e. g. across the wine .span of the hypothetical aeroplane aforesaid). I a Preferablyfalso means are incorporated to mask rromthe j gunner's vlsionpduring the aiming peration, hoththe teenage manger spot? thatitprojects on tothe target;

There will nowhe-given, withreierenceto the a accompanying drawings, a description of onev convenient construction of a device in accordance i with theinvention andillustrative thereof. It is 3 however clearly to be understood that the illus trated device has been selected for description, merely by way of exemplifllca ion of the inventlon, and not in limltation thereoi'.

on the optic headof a computing gun sight a d some internal parts of theoptic head are shownpff Fig. 2is a plan viewr'r If i :v Fig. 15s horizontal axial section through the projector device; showing its internalconstruw tion and drawn toa larger scale than Figs. i and 2; q l Fig. 411$ a wiring diagram for a fire control 45 lndicatingrgarrangement; and

Fig...5is agscheinaticshowing oi theapparatus-l I mounted on a standard gun mounting, and illus-I I tratlngtthe manner oiuse ofQtheIvisible sighting indicia..,.. r i i 1 iiiust i has the1inventionas applijedto a as with which the slghtlis intended to be used, and f 1 beamiollows the movements of the line of sightt} i Fig; 1 is a sideelevation or the device mounted I an optic head rotatably mounted thereon. The optic head contains the optical parts of the sighting apparatus that define the direction in which the sight is aligned, i. e., defines the line of sight that the gunner has to keep on a target in aiming the gun. Reference II, in Fig. 1, denotes generally the optic head, which is fixedly mounted on data transmission casing 2|! rotatable about the normally vertical axis X-X with respect to the azimuth to compute a correction which is applied to turn the optic head ll of the sighting apparatus about the axis X-X through an angle related, in the manner described in the aforementioned U. 8. application No. 358,382, to the azimuth correction to be imparted to the gun.

As illustrated in Fig. 5, the training device assembly comprises an optic head ll, mounted on a machine gun data transmission casing 22, which is secured, in the usual manner, on machine gun 60, having a barrel II, and supported on a mount, indicated generally at 02. A screen, II, is set up at a suitable distance from the machine gun mount, and will support a model target II, or a projected image thereof. The student gunners line of sight to the target is indicated generally by 12, while the instructor's separate line of sight is indicated by 12. A special projector ll, mounted on the optic head 10, is arranged to project a beam ll of colored light, which beam forms a light spot II on the screen. This light spot is of any suitable color, such as red, and is masked from the view of the gunner by being neutralized by a complementary filter of green, so that he sees only the target II and not the light spot It. The optical axes of the machine gun barrel, the optic head, and the beam projector are mounted for simultaneous parallel operation, so that the several lines of sight and the light beam converge at the target, as will be described more in detail herein.

The optic head includes a light source I, a range light gate 2, an inclined tilting mirror 2, a lens 4, an inclined reflecting plate glass window 8 and a color filter 6, which may, for instance, be a green glass filter. Light emanating from the source I passes through the range light gate 2, which has a horizontal and a vertical cross line (not shown) and is capable of adjustment for target dimensions and range as described in the aforesaid U. 8. application. This light then impingesonthemirrorlwhichisfixedtoarocking member 21 pivoted at 21' ior movement about a horizontal axis perpendicular to the direction of incidence of the light. The mirror 2 is normally positionedatanangleof45 withrespecttothe incident light. After reflection upwards by this mirror, the light passes through the collimating lens 4 and impinges, in a substantially parallel beam, on theinclined window 8, from which it is reflected to the gunners eye. The lens produces a virtual image of the range light gate 2 at along distance from the lens (infinite if the lens is adjusted to produce a truly mrallel beam) and, as the gunner views this image in the refiecting window I, it appears to him to lie in the general direction of the target, 1' I, which he is viewing through the said window. In directing the line of sight, 1:, on the target the gunner aligns the point of intersection of the cross-lines of the image of the range light gate 2 (which constitutes the foresight of the sighting apparatus) on the target as seen by him through the window I (which constitutes the back sight). The mirror 2 is tilted by the computor (through the agency of the member 21, which includes a toothed sector meshing with a driving pinion it) so as to apply the elevationai correction that it calculates to the line of sight; this alters the direction of the line of sight leading from the window to the image of the crosslines of the range light gate.

The device of the present invention comprises an optical light projector the case H of which is mounted on a pair of pintles i2 (Figs. I and 2) for movement in a vertical plane about a horiaontal axis. The pintles II are screwed adjustably into the opposite limbs of a forked bearing bracket i2 which, in turn, is adjustably fixed on the top of the case of the optic head II. The purpose of this projector is to throw a beam of light, It, substantially in the same direction as the line of sight. Within the projector case Ii is housed a lamp l2 (Fig. 3) carried in an adjustably mounted lamp holder It and the optical projecting system comprises a condenser lens ll, an iris diaphragm unit II, a projector lens I. and a color filter II, which might be mounted in the vicinity of the projector lens instead of being adjacent the condenser lens, as shown.

It is the purpose of the filter II to impart to the projected light beam a color to which the filter I in the optic head-is opaque. Thus, in conjunction with a green glass filter i, a red glass filter I! would be appropriate.

The iris diaphragm unit II is of a conventional type, its leaves being movable by means of a lover II and a spring ll", acting on this lever, tends to keep the stop at maximum aperture. The manner in which the aperture is varied, in accordance with the setting of the range light gate 2 will appear hereinafter.

The movement of the projector about its horizontal axis (pivots I2) is made to correspond with the movement of the mirror 2 about its axis of rotation. For this purpou a link ll (Fig. l) is pivotally connected at II to the projector case ii and is also pivotally connected at I! to a short eyebolt 22 which, in turn, is secured to one end of a lever 2| by nuts 20' manipulation of which permits the free length of said eyebolt to be adjusted. Leva- 2| is pivoted centrally, at 2|, for movement in a normally vertical plane and it carries, at its other end, a roller 22 resting on a plate 23 on the upper end of a push rod 2. slidable in a sleeve 2i fixed in the casing of the optic head.

The lower end of the push rod 24 rests on a roller 20 carried by the tilting member 21, controlled by the computer mechanism and rigidly supporting the mirror 2 as hereinbefore explained. The centre of gravity of the projector is located at a point forward of its pivotal axis. so that under all operating conditions contact is maintained between the roller 22 and the plate 22.

The linkage is so arranged that the axis of the projector and the line of sight maintain a constant relationship. For this purpose. the said linkageisdesigned toensurethattheangular movement of projector case ll about the axis of its pivots I2 is, for small angles of rotation, substantially one-half of the angular movement of the mirror-2, about its axis of rotation (pivots 21) and isin the opposite directions-The lever ill of the iris diaphragm l is connected by a Bowden transmission 28 with the range light gate 2 and is adjusted so that the diameter ortheirls produces a light-spot, 15, which just frames the it target, it, aimed at whenjthe said targetis accurately framed in the range light gatei moreover the design andarr lflfimentare such that the, diameter oi the iris aperture is ,varied proportionately with variations inthe apparent dir meter of the range light gate. A stop bracket for the projector end. of the Bowden casing is indicated at 8! andlil'isan adjuster has;

-'Ioenable an instructor to check the gunnerfs iire control, byviewing thejtarget along line, or] sight It, the circuit ofthefprojectorlamp iamay be arranged as shown inFig. 4. A. firing switch '32, fitted in the gunturret,-fis ofjthe well-known press-to-break type and 33 isa resistance for, regulating the: voltage supplied to lamp '13.] j The 1 lamp. the resistance and thenrmg switchare connected in series acrossthefcurrentl supply terminals 34 but the flringzswitch isshuntedfby a flasher switch "which may comprise am e-- chanical make-and break (indicated byloam 13B)? and may be driven continuously from the drive motor gear train 01' thejguni ;It will be seen that, with this arrangement, although the flasher switch is in continuous operation,; it can be citedtive to flicker the projector light only when the shunt circuit through the firing switch isfopened,

by reason of the gunner depressing the said firing switch. When the gunner is notflring. that is to say, when he'is not depressing the switch 32, the

- latter stays closed and short circuits the flasher coincides with a mark on a screen at the distance or mean distance at which the dummy target or target image is to be followed during training operations. The collimating lens 4 is then adjusted until there is no apparent shift of the image of the cross-lines relative to the mark if the gunner moves his head so as to look at the mark through a different part of the window 5. The lamp I8 is adjusted centrally with respect to the beam it produces and the projector lens 16 is adjusted and focussed for sharp definition of the light-spot produced by the beam ll impinging on the screen 10. The projector is then aligned by small adjustments of the bearing bracket l2 relatively to the top of the optic head liland also by fine adjustment of the length of the eyebolt 20, so that the cross-lines from the range light gate, when seen in the reflecting window 5, are centrally placed on the light-spot I5. The sight is then turned until a target is sighted, i. e., until the cross-lines of the image of the range light gate are centred upon the dummy or'practice target, which may be an image 1| oi. an aircraft projected on to the screen. The iris diaphragm I5 is adjusted by effectively lengthening orshortening the wire of Bowden transmission 28 by manipulating the nut 29, until the light-spot just frames the target. vThe device is now adjusted for use. I

For training purposes the sighting apparatus anew/4a iflite fs thathew bw d sar ed de ice mane mounted inva., gun-.-turret or dummy gun-turret,

and atarget may. as already'intimated, be projected onto a cinematograph screen. ,During operations by" the gunnefrithe computing mochanism. turns thei optic lhead. l flhrelatively to ithe ,baseoi. the'apparatus and also tilts the mirror in a directionflperpendicular to the saidbase, by computed in amounts, thus applying continuous y to the line of sight: varyingfmovements in two p rpenai'cumpian s- Bincethe projectoris rigidlyflxed to L the optic head {and the,11ne of i mumsflwith ,lth'efioptic head, the. projected f beam receives the same. movement, in the Same direction relative to the base. asdoestheTlineKoi sight; Further, as previouslyeizplainedthe linka e a, between mirrorizt and" the pro ector moves the projector through aniangle equal tohaliithat moved through by. the mirror and thereijorefequal to the angle movedthrough by the line oi sight. The axis oi the beam, therefore, moves in corre- ,1 sponde'nce with the line of sight. The gunner 2; tracks the target .bykdefllnithlinflOf sight I [aligned von it and ranges thetarget by keeping it i framedfin' the range light gate. The. projector projects onto the screen a light-spot which corresponds with the trackingand rangingoi the er. andl'ience shouldbe maintained centredon the target'andiramingit', as the size oftheitargetYimage, is varied in accordance with the up- J parentldistance oi the target from the gunner.

' "are complementary; and neutralize each other, the} "eii'ectu being to prevent the gunner hi'rom seeing thelight-spot and using it to iollomthe Thei' ejd and reen fi ers ill the bath of the beam andjin the gunner's field of vision. respectively,

target instead of aiming by means of his line of sights When thegunner considers thathe is tracking and ranging accurately he depressesjthe firing switch andrenders the flasher switch eilective in the manner and "for the purpose already explained. V weyclaim; I L'Ap ratus for supervising gunnery practice wherein'an optical gum-sight mechanism isaixned at atarget, and the gunner sees anunmodiiled targetlinthe gun sight,the improved system for indicating the resulting aim to an instructor with out knowledge ofthe'gunner, comprising means operable by manipulation of the gun-sight mechanism to project a visual indication on the tar-- get in register with the line of sight of the. gun

I sight, and separate means in the gun-sight mechanism for. masking said .visual indicationirom the gunner only.

manipulation of the gun -sight mechanism ito project a visual: indication on the target in register with the line of sight of the gun sight andvisible to anobserver, and separate means in theoptical system of the gun-sight for maskingsaidfvisual indicationfrom the gunner, the visual indication being variable in size and intensity by and with, 01. the gun-sight range-setting the range-finder apparatus. h a

3. Apparatus iorsupervising gunnery pracs tice wherein an optical gun-sight mechanism is aimed at a target. comprising means operable by manipulation of the gun-sight mechanism to pro-l lect a beam of light and'impose a visiblelight spotonlthe target in register with theline' of sight of the gun sight, and separate optical means in the gtmsight tor neutraiiaingthe light spot and leave only the \mmodified target visible to the amber.

4. Apparatus for supervising gimnery practice whereinsnoptical gun-sightmechanismisaimed at a target. comprising means operable by .manipulation of the gun-sight mechanism to impose a light spot on the target. co-diametral therewith. and in register with the line of sight of the gun sight. and separate optical means in the gun sight for neutralising the 'light Spot without afiecting'the visibility oi the target to the gunner, whereby the gtmn'er sees only the target. and an observer can observe the opposition of the light spot to and on the target and determine the accuracy oi the gunner.

8. Apparatus for supervising gunnery practice wherein a gun-sight mechanism having an optical sighting system is aimed at a target, comprising means operable by manipulation oi the glm-sight mechanism to impose a co-diametral light spot on the target and to intermittently register with the imageviewed in the line oi sight of the gun sight, and separate optical filter means in the gun sight for neutralizing the light spot without afiecting the gunner's visibility of the target image.

6. Apparatus for supervising gunnery prac tice wherein a gun-sight mechanism having an optical sighting system is aimed at a target,

' comprising means operable by manipulation oi the gun-sight mechanism to prolect a controlled -red ishtsp'tonthetarsetinregister tem tor neutralizing said colored uncolored target visible to the gunner.

tapparatusiorsupcrvisinggunnerypractice whereinagun-sightmechanismhavinganop-v ticalsightingsystemisaimedatatargethra lationorthegim-aightmechanismtoimpoaea withthe lineoisiahtotthegunsightandgreen filters'insaidopticalligh elective ns toneutraliaesaidredlightspotsothatthegunwherein a gun-sight mechanism having an opticalsightlngsntemisaimedatatargetbya gunner,.-and an instructor visually checks the target-to determine accuracy or the gunner's 'aim, comprising mans operable by manipulation oi the gun-sight mechanism to impose a colored light spot on the target in register with the line of sight of the gun-sight and commementary color filters inthe optical l hting III- l ht I I that the gunner is able to see only the original -target,whiletheinstructorisabletoseeboththe prising means operable by manipulation oi the.

gun-sight mechanism to project a colored, visual indication on the target, in register with the line of sight of the gun-sight, means variable by and with the range-finder of the min-slam r noriginal target and the colored light spot imposed thereon.

ALBERT B1001). ARTHUR PHILIP GLINNY.

nun-emcee crrm The following references are of record in the file of this patent:

UNITED STATES PATENTS Date Number Name Re. 12,916 l'iske Feb. 9, 1000 2,230,149 wedd ngton Jan. 28, 1941 2,268,113 l'ldelman Dec. 80. 1941 2,331,616 Minghettl Oct. 12,1943

2,364,720 Jo'nes Dec. 13, 19 

